The present invention relates to a magnetic head slider and, more particularly, to a so-called negative pressure type head slider for use in a magnetic disk drive.
To meet the increasing demand for a magnetic disk drive with a high density recording capability, attempts have been made to reduce a gap between a magnetic head and a recording medium. As for the mechanical reliability of the disk drive itself, the key is the configuration of the interface between a magnetic head slider and a magnetic disk, as keenly discussed today.
When a magnetic head slider and a magnetic disk contact and slide on each other, dust or powder is produced at an air bearing surface (ABS) between the slider and the disk. The dust is one of factors that degrade the mechanical reliability of the disk drive. The decreasing gap between the head and the disk, i.e., the decreasing amount of light of the head slider increases the chance of contact of the head slider and disk not only at the time of contact start and stop (CSS) but also at the time of track access and usual flight. In this respect, the dust problem is becoming more critical.
Specifically, when the dust deposits on the ABS and side walls of the head slider, it varies the flying characteristic of the head slider and brings about a head crash. Moreover, the dust deposited on a write/read device results in defective recording and reproduction. In addition, the dust caught between the head slider and the disk is apt to scratch the disk or the slider or is apt to cause the slider and disk to adhere to each other to thereby practically disable the disk drive.
Japanese Patent Laid-Open Publication No. 4-117680 (Document 1 hereinafter) teaches a magnetic head slider so configured as not to catch the dust between it and a magnetic disk or stick or the disk when a magnetic disk drive is out of operation. This head slider includes side rails formed with obliquely extending grooves by machining. Japanese Patent Laid-Open Publication No. 4-67485 (Document 2 hereinafter) discloses a magnetic head slider including side rails formed with a number of straight grooves in an ABS surface thereof by lapping. Further, Japanese Patent Laid-Open Publication No. 6-208772 (Document 3) proposes a magnetic head slider formed with grooves perpendicular to the direction of an air stream in its tapered or chamfered surface which is located at the air inlet end of the slider. With the grooves formed in the tapered surface, the head slider discharges the previously mentioned dust, as well as dust introduced from the outside, in order to obviate head crashes.
The above conventional head sliders each has some problems left unsolved, as follows. The head sliders taught in Document 1 and 2 cause the dust to deposition the side walls of the grooves formed in the side rails. The angle between the side walls and the bottom wall of each groove is generally greater than 90 degrees inclusive although it depends on the machining method. As the above angle increases, the dust deposits on the side walls more easily and aggravates the probability of head crash. This is because the dust on the side walls appears on the ABS and deteriorates the flying characteristic of the head slider, and because the dust forming a mass is easily caught between the slider and the disk.
The head slider proposed in Document 3 is not desirable as a low flight type head slider adapted for high density recording. Specifically, the head slider introduces dust produced from a magnetic disk into the grooves of the tapered portion and causes it to drop onto the disk in the form of amass of suitable size. Such a mass is a critical cause of head crash because a head slider for used in an advanced magnetic head drive flies only about 0.1 .mu.m or less.
Further, the head slider of Document 3 is not desirable as a low flying height, negative pressure type head slider. Specifically, a low flying height head slider is processed by ion milling or similar method more accurate than tapering, chamfering or similar machining customarily applied to head sliders.
As stated above, the conventional head sliders each lacks means for sufficiently coping with head crashes ascribable to the dust derived from the contact of the slider and a magnetic disk.
Technologies relating to the present invention are also taught in, e.g., Japanese Patent Laid-Open Publication Nos. 63-298879, 4-188479, 4-228157, 5-128468, 6-44719, and 6-52646.